Sandwich type boards for outdoor use are already well known. These boards are made of different layers of wood and cellulose material with impregnations, which are then pressed to form a compact board.
These well-known boards have disadvantages, namely:
Physical-chemical contamination of the different layers of the board impregnated in different resins.
Little chromatic adaptability to the requirements of the different customers.
Little surface finish adaptability in the final presentation of the board.
Low resistance to environmental physical-chemical conditions, for example, ultraviolet rays.
A package of cellulose sheets impregnated in phenolic resin is usually used as the core for these boards. Over this, and on each side, a thin panel, for example 0.5 mm., of wood is fitted, also impregnated in phenolic resin. The rougher and darker pigmentation of the core easily passes to the wood panel, contaminating it and modifying its outer aspect.
To avoid this, a cellulose film, impregnated in melamine, is placed between the core and the wood panel, acting as a physical-chemical barrier.
The durability, functionality and aspect of these boards depend on the number of layers of different materials used and the type of impregnation resin, so there are infinite combinations and only a few of them give practical results, one of which being the combination targeted by this invention.
The surface resistance to the sun""s radiation, mainly to ultraviolet rays (UV rays), is achieved by providing the outside of the sandwich with an acrylic type film, but in laboratory practice, the applicant has observed that a sandwich-board with just an acrylic film on the outside does not pass the boiling immersion test for two hours, giving rise to bubbles and deformation.
The applicant has also overcome this obstacle by converting the acrylic film into a multi-layer film comprised of an acrylic type transparent/translucent film and an absorbent cellulose film, which will also be transparent/translucent when impregnated with a resin of the same nature as that used to impregnate the previous layer of the sandwich. Both films are joined together with an adhesive.